Combined print hammer module and printed circuit board

ABSTRACT

There is disclosed a fragmentary portion of a printer having print hammer modules, each module having a frame, print hammers, and print hammer operators, and a printed circuit board.

United States Patent Inventor John Guzak, Jr. 2,915,968 12/1959 Witt et a1. 101/93 Waukegan,l11. 2,940,385 6/1960 House 101/93 AppLNo. 728,606 2,955,755 10/1960 Bradshaw. 101/19X Filed May 13,1968 2,955,758 10/1960 Jones 101/19 X Patented July 20,1971 3,118,721 1/1964 Exline 101/93X Assignee SCM Corporation 3,233,224 2/1966 Foster et a1. 101/93 X New York,N.Y. 3,289,575 12/1966 Wasserman 101/93 3,349,646 10/1967 Potter 101/93 3,418,928 12/1968 Ponzano 101/93 COMBINED PRINT HAMMER MODULE AND 3,429,258 2/1969 Baranoifet a] 101/110 x PRINTED CIRCUIT BOARD 3,499,382 3/1970 Potter et a1. 101/93 5 Claims, 4 Drawing Figs. P E w B P nmary xammer 1 ram enn u.s.u 101 93, h

OI/L339, arney osep J. Grass lnt.Cl B41] 9/10, HOSk 1/ 12 Field of Search 101/93 C, 19,110,1;339/17;317/117 ABSTRACT: There is disclosed a fragmentary portion of a References printer having print hammer modules, each module having a UNITED STATES PATENTS frame, print hammers, and print hammer operators, and :1 2,874,634 2/1959 Hense 101/93 printed circuit board.

78 EEEE. :fFF 3 o 1H Q 2 6 I Q Q9 50 Q (9-58 m 11 29' I AZ Q Z 4 G) w f 4 5 W55 59 55 Q 22 1 \1\ 55 1 e I 1 14 l 1 2c, 22 Z 25%, lo l 9 15 1e '1 i I 12 15 PATENTED JULZO Ian K m m m B n w COMBINED PRINT HAMMER MODULE AND PRINTED CIRCUIT BOARD BACKGROUND OF TH E INVENTION 1. Field of the Invention This invention relates to a high speed printer and in particular to print hammer modules for such a printer.

2. Description of the Prior Art Printers with print hammer modules are known in the art.

SUMMARY OF THE INVENTION The invention provides a compact construction by which access to adjustable printer components is attained, and by which ease of assembly and manufacture is facilitated.

The invention is useful where either single or plural print hammer modules are provided. In printers having plural print hammer modules, that is, a whole bank of modules, the space between the modules is small. By combining a printed circuit board for each module, space is conserved, and this space is available for specific purposes, for example, for adjusting the print hammers and for mounting electronic components such as diodes, transistors, and so on.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially broken away perspective view of a portion of a drum printer and shows an assembled group of print hammer modules secured on stationary frame structure in accordance with one embodiment of the present invention;

FIG. 2 is a side elevational view ofa print hammer module and a fragmentary portion of a print symbol carrier shown in FIG. I;

FIG. 3 is a sectional view taken along line 34 of FIG. 2; and

FIG. 4 is a fragmentary perspective view of a hammer operator assembly in conjunction with a printed circuit board.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, FIG. 1 depicts the arrangement of a print drum and a series of print hammer modules. The modules are individually clamped in module frame structure secured to the printer frame Each module has print hammers adapted for movement into printing cooperation with the print drum and an equal number of hammer operator assemblies. Ready ad justment of the print hammers is provided while the modules are held clamped in the module frame structure and any module is removable from the module frame structure without disturbing the other modules.

Referring in particular to FIGS. 1 and 2 of the drawings, there is shown a fragmentary portion of a data communication printer generally indicated at 10. A moving print symbol carrier 11 is shown in the form of a rotating print drum, although a belt-type or any other suitable type of print symbol carrier could be used. The symbol carrier 11 is shown to have rows of identical print symbol or raised type elements 12. A series of print hammer modules 13 are stacked in vertical side-by-side relationship in frame structure generally indicated at 14. The frame structure 14 is shown to include support plates 16 and 17 at each end of a baseplate l8, and bars or braces 19, 20 and 21 interconnecting the support plates 16 and H7 by means of threaded fasteners 22. The baseplate 18, extending normally with respect to the modules I3, is adjustably secured to the frame 15 of the printer by machine screws 23 (only one of which is shown) which extend through enlarged bores 24 in the printer frame,l5. The baseplate 18 is suitably secured as by threaded fasteners (not shown) to the support plates 16 and 17. Side guides are secured to the frame by threaded fasteners 26'which extend through enlarged bores 27 in the guides 25 and are threadably received in the frame 15. Once the frame structure 14 is aligned with the print symbol carrier 11, the threaded fasteners 26 can be tightened and thereafter the frame structure 14 can be slid out of position and subsequently slid back into position without further adjustment.

The print hammer modules 13 shown in FIG. 1 are identical for the sake of interchangeability and economy, and hence only one print hammer module 13 is shown in detail in FIG. 2. Each module 13 has a frame 23 which is shown to be of planar from and, in particular, the frame 23 is flat. The frame 28 is preferably blanked out of a single piece of metal, as shown, but it can be composed of or formed from other suitable materials as well. Comb structure 30 :is mounted to one side of the frame 2B by threaded fasteners 29. A pivot 36 mounts print hammers 35 about a common axis 36'. A compression spring 38 serves to urge each respective print hammer 35 to a normal position out of printing cooperation with the print symbol carrier 11. All the print hammers 35 are shown to be identical and generally L-shaped in construction and have a long lever arm 39 terminating at its free end at a print or hammer head having a smooth or uninterrupted contour face 40', each print hammer 35 has a bore 35; and the print hammers 35 also have short actuating lever arms 41, 42, 43 and 44 which are shorter than the lever arms 39, which are angularly offset from the lever arms 39, and which extend radially outwardly from the axis 36. In particular, the actuating lever arms 41, 42, 43 and 44 form teeth of a circular gear segment. The axis of the gear segment is common with the axis 36'. The lever arms 41, 42, 43 and 44 have involute contoured faces in structural rolling pairing cooperation with respective involute contoured faces at abutment ends 45', 46', 47 and 48' of hammer operator levers 45, 46, 47 and 48. Hammer operator assemblies 49, 50, 51 and and their hammer operator levers 45, 46, 47 and 48 are disposed at equally spaced-apart locations to the frame 28, so that each hammer operator assembly and its respective hammer operator lever has a different angular disposition about the axis 36 to provide an angular array of operator assemblies. The hammer operator levers 45 and 46 are bent inwardly toward the hammer operator levers 47 and 48, and the hammer operator levers 47 and 48 are bent inwardly toward the hammer operator levers 45 and 46. The print hammers 35 are equally spaced apart and ends 45', 46, 47 and 48' terminate in adjacent and aligned relationship with respective lever arms 41, 42, 43 and 44. The actuating lever arms 41, 42, 43 and 44 are shown to be at least equal in number to the number of hammer operator assemblies 49, 50,51 and 52. The hammer operator levers form part of respective hammer operator assemblies generally indicated at 49, 50, 51 and 52.

The hammer operator assemblies 49, 50, 51 and 52 are arranged in a planar form so that four or more occupy no more lateral width than would one hammer operator assembly. Each hammer operator assembly 49, 50, 51 and 52 includes an electromagnet 53 having a relatively thin U-shaped core 54, a print coil 55, and relatively flat armature 56 composed of magnetizable plates 57 secured to its respective hammer operator lever. The arrnatures 56 and the respective hammer operator levers 41, 42, 43 and 44 are each pivotal as a unit about respective pivots 58 secured in. the frame 28. Studs 60 secured in the frame 28 threadably receive stop screws 61 which provide an adjustable stop device for the ends of the levers 45, 46, 47 and 48. The springs 38 normally urge the print hammers 35 counterclockwise, as viewed in FIG. 2, and urge respective levers 45, 46, 47 and 48 clockwise away from pole faces 54' of respective electromagnets. Thus, the ends of the levers 45, 46, 47 and 48 normally abut their respective stop screws 61, as shown in FIG. 2. In FIG. 2 only the first of the four print hammers 35 and springs 38 are seen, the remaining three print hammers 35 and springs 38 being hidden behind them. When the print coil 55 of the selected hammer operator assembly 49 is energized, the armature 56 and its associated hammer operator lever 45 is pivoted counterclockwise, and involute contoured face at end 45', being in driving engagement with the involute contoured face of the actuating lever arm 4!, drives its respective selected first print hammer 35 clockwise into printing cooperation with a print symbol 12 on the print symbol carrier 11.

Inked ribbon R shifts up into the path of the head 40 of the print hammer 35 each time a print hammer 35 is shifted into printing cooperation with the print symbol carrier 11. A record medium R is fed stepwise in line-feed direction between the print symbol carrier 11 and the inked ribbon R by structure (not shown). Neither the inked ribbon R nor the record medium R are shown in FIG. 1 for the sake of clarity. As soon as the print hammers 35 are driven out of contact with the ribbon R by the biasing forces of their respective springs 38 and hammer rebound after the symbols have been printed, the ribbon R is shifted downwardly to the position shown in FIG. 2. The symbol or symbols printed in a line on the record medium R can be read when looking down from above the modules due to the fact that ribbon R is out of the way and the modules are so constructed that they do not obstruct the view. The modules 13 terminate only a short distance above the hammer heads 40 and the comb structure 29 is disposed entirely below the hammer heads 40. By way of example, not limitation, each module is about 0.33 of an inch wide.

A printed circuit board 62 associated with its respective module 13 is preferably secured to its module frame 28 by an adhesive 62. Although a printed circuit board 62 with only one layer is shown, a multilayered circuit board can be used, if desired. The printed circuit board 62 is shown to have a plastic insulating base 63. and conductors 64 and 64' printed on the base 63. The conductors 64 and 64' extend around the ends of the operator assemblies 49 through 52 in a generally C-shaped arrangement. Conductors 64' provide circuit connections for the coils 55. The conductors 64 and 64' are connected to respective diodes 55 and coils 55 of hammer operator assemblies 49, 50, 51 and 52, respectively. The diodes 55' suppress the inductive kick of the respective coils 55. Transistors (not shown) and various other printer logic components can be mounted to the base 63 and connecting conductors 64 and/or 64', if desired. The conductors 64 and 64' are connected to individual conductors 65 which extend through respective enlarged bores 66 in flange portion 68 of the frame 28. The conductors 65 are molded into a plug board 69 and their plug terminals 65 extend into sockets 70 molded in a connector board 70. A plug board 69 is suitably secured to each flange portion 68. The connector board 70 extends the full length of the frame 14 and its sockets 70' are in alignment with plug terminals 65 of all the plug boards 69. Prongs 71 which extend into sockets 70' are connected to printer circuitry (not shown).

Any module or modules 13 are individually removable from the frame 14 without disturbing the remaining modules 13 in the frame 14. As best shown in FIG. 1, each module 13 is individually clamped in the frame 14 by a clamp element 72 and its associated threaded fastener 73 which, when tightened, urges its respective module frame 28 against a bar 21. The baseplate 18 has parallel equally spaced-apart grooves 74 into which the module frames 28 extend. The grooves 74 provide only enough clearance to provide for insertion and removal of the modules 13. The grooves are accurately located and serve to locate the modules 13 and to hold them in their located positions. When it is desired to remove a module 13, its respective threaded fastener 73 is loosened and the clamp element 72 is rotated 90'', out of the path of the module. Threaded fasteners 22 which hold the brace 19 in position are unthreaded and the brace 19 is removed. As clamping surface 75 of each module 13 is parallel with the bottom of the associated groove 74, and as spring-urged ball 76 offers only slight frictional resistance, the module can be easily pulled out of the frame structure 14. While the module 13 is being pulled out of the frame structure 14, the plug terminals 65 withdraw from sockets 70'. Should it be desired to return the removed module 13 to its former position in the frame structure 14, it is merely slid back into the position it formerly occupied in the frame structure. Each ball 76 exerts only slight pressure on the surface 75 of its respective module 13, and urges the module frame 28 against the baseplate 18. The force of each spring 77 is regulatable by means of a set screw 78. The ball 76 and the spring 77 form a resilient clamping structure 79, and there is one such clamping structure 79 for each module frame 28 although only one is shown in FIG. 2.

During the printing operation, the symbol carrier rotates at a constant rate. If a particular symbol such as a G is to be printed at a particular location along the line, the head 40 of the proper print hammer 35 is driven into printing cooperation with the print symbol "G" when it is presented in front of that print head 40. Should it happen that the printed line is slightly uneven, it indicates that one or more of the print hammers 35 is driven into printing cooperation with the selected symbol element 12 either too early or too late. With the symbol carrier 11 rotating in the direction indicated by arrow A in FIG. 2, assuming a symbol is printed too high with respect to other symbols in the line as a result of the print hammer 35 arriving too late at the printing location, an adjustment can be made in the stop screw 61 of its associated hammer operator assembly; namely, the stop screw 61 should be turned to bring the armature 56 closer to the pole face 54 of the electromagnet 53. The head 40 of that print hammer 35 will then be in a return stop position in closer proximity to the symbol carrier 11. Thereafter, when the coil 55 of that hammer operator assembly is energized, the print hammer 35 will effect recording of the symbol in line with the other symbols in the line, assuming the stop screw 61 has been correctly adjusted. The compactness of the arrangement of print hammer module and printed circuit board allows the adjusting screws 61 to be clearly visible to the person making the adjustment without the hindrance of a maze of insulated wires. In addition, the chance of wires becoming disconnected is greatly minimized, thereby increasing reliability. Assuming now that a symbol is printed too low with respect to other symbols in the line as a result of the print hammer 35 arriving too early at the printing location, an adjustment can be made in the stop screw 61 of its associated hammer operator assembly; namely, the stop screw 61 should be turned to bring the armature 56 further away from the pole face 54 of the electromagnet. The head 40 of the print hammer 35 will then be in a normal stop position further away from symbol carrier 11. Thereafter, when the coil 55 of that hammer operator assembly is energized, the print hammer 35 will effect recording of the symbol in line with the other symbols in the line, assuming the stop screw 61 has been correctly adjusted. Each core 54 of each electromagnet 53 is adjustable with respect to the frame 28 by virtue of machine screws 54 threadably received by the frame 28 which extend through enlarged bores 54'. It is preferred that the adjustment of each electromagnet be such that its respective armature abuts the pole face 54' before the head 40 of the print hammer 35 strikes the ribbon R, thus providing a predetermined amount of separation or loss of contact between the hammer operator lever and its related print hammer and free flight of the print hammer. The ends 45, 46, 47 and 48 and the lever arms 41, 42, 43 and 44 are so dimensioned that such separation therebetween is capable of taking place, as indicated in FIG. 2.

The print hammer module 13 can be mounted by a carriage, as shown in said US. application, if desired. A carriage guide rod can extend through an enlarged bore 82 in the module frame 28, also shown in said application. The carriage can be actuated by any suitable means, not shown in said application but disclosed, for example, in US. Pat. No. 3,280,256.

Other embodiments and modifications of this invention will suggest themselves to those skilled in the art, and all such of these as come within the spirit of this invention are included within its scope as best defined by the appended claims.

lclaim:

1. An impact printing apparatus including a plurality of electronically driven print hammers which strike a recording surface at an impact zone, wherein the improvement comprises:

modules carrying groups of print hammers, print hammer driving mechanisms, and first 'electrical contact means for supplying electrical power to said driving mechanisms;

means defining positioning channels approximately perpendicular to the recording surface at the impact zone into which said modules may be slid into printing position;

fastening means for securing said modules in printing position; and

second electrical contact means positioned adjacent the means defining positioning channels and engaging said first electrical contact means on each module when the module is in printing position;

whereby each module may be easily and quickly removed from and returned to said printing apparatus.

2. An impact printer in accordance with claim 1 wherein the modules also carry a printed circuit board supporting printed circuits which couple the first electrical contact means to the driving mechanisms.

3. An impact printer in accordance with claim 2 wherein at least part of the control circuitry for the driving mechanisms is attached to the printed circuit board.

4. An impact printer in accordance with claim 1 wherein the modules are planar and wherein the positioning channels engage the module edges.

5. An impact printer in accordance with claim 1 wherein the fastening means for each module include an elongated, pivotable lever perpendicularly attached to the end of the corresponding means defining a positioning channel and adjustable screw means passing through said lever and into the means defining a positioning channel, whereby a module can be removed by loosening the corresponding screw means and rotating the corresponding lever. 

1. An impact printing apparatus including a plurality of electronically driven print hammers which strike a recording surface at an impact zone, wherein the improvement comprises: modules carrying groups of print hammers, print hammer driving mechanisms, and first electrical contact means for supplying electrical power to said driving mechanisms; means defining positioning channels approximately perpendicular to the recording surface at the impact zone into which said modules may be slid into printing position; fastening means for securing said modules in printing position; and second electrical contact means positioned adjacent the means defining positioning channels and engaging said first electrical contact means on each module when the module is in printing position; whereby each module may be easily and quickly removed from and returned to said printing apparatus.
 2. An impact printer in accordance with claim 1 wherein the modules also carry a printed circuit board supporting printed circuits which couple the first electrical contact means to the driving mechanisms.
 3. An impact printer in accordance with claim 2 wherein at least part of the control circuitry for the driving mechanisms is attached to the printed circuit board.
 4. An impact printer in accordance with claim 1 wherein the modules are planar and wherein the positioning channels engage the module edges.
 5. An impact printer in accordance with claim 1 wherein the fastening means for each module include an elongated, pivotable lever perpendicularly attached to the end of the corresponding means defining a positioning channel and adjustable screw means passing through said lever and into the means defining a positioning channel, whereby a module can be removed by loosening the corresponding screw means and rotating the corresponding lever. 